U.S. patent application number 11/796937 was filed with the patent office on 2007-11-15 for patent foramen ovale (pfo) closure method and device.
This patent application is currently assigned to NMT Medical, Inc.. Invention is credited to Andrzej J. Chanduszko, Carol A. Devellian, Steven W. Opolski.
Application Number | 20070265642 11/796937 |
Document ID | / |
Family ID | 23363283 |
Filed Date | 2007-11-15 |
United States Patent
Application |
20070265642 |
Kind Code |
A1 |
Chanduszko; Andrzej J. ; et
al. |
November 15, 2007 |
Patent foramen ovale (PFO) closure method and device
Abstract
The present invention provides methods and devices for closing
two overlapping layers of tissue in a mammalian heart, for example
a patent foramen ovale (PFO). The closure devices may take a number
of different forms and may be retrievable. In some embodiments, a
device is sized and shaped to extend from septum secundum, into the
left atrium, through septum primum, and into the right atrium, such
that the first and second ends cooperate to provide a compressive
force to the overlapping layers of tissue. In some embodiments, the
closure devices may be delivered with a catheter capable of
puncturing mammalian tissue.
Inventors: |
Chanduszko; Andrzej J.;
(South Boston, MA) ; Opolski; Steven W.;
(Carlisle, MA) ; Devellian; Carol A.; (Topsfield,
MA) |
Correspondence
Address: |
WILMER CUTLER PICKERING HALE AND DORR LLP
60 STATE STREET
BOSTON
MA
02109
US
|
Assignee: |
NMT Medical, Inc.
Boston
MA
|
Family ID: |
23363283 |
Appl. No.: |
11/796937 |
Filed: |
April 30, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10341802 |
Jan 14, 2003 |
7220265 |
|
|
11796937 |
Apr 30, 2007 |
|
|
|
60347336 |
Jan 14, 2002 |
|
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|
Current U.S.
Class: |
606/151 |
Current CPC
Class: |
A61B 2017/00615
20130101; A61B 17/0644 20130101; A61B 2017/00867 20130101; A61B
17/068 20130101; A61B 2017/00575 20130101; A61B 2017/00579
20130101; A61B 2017/00592 20130101; A61B 17/0057 20130101 |
Class at
Publication: |
606/151 |
International
Class: |
A61B 17/08 20060101
A61B017/08 |
Claims
1. A device for closing two overlapping layers of septum primum and
septum secundum dividing a left atrium and a right atrium in a
mammalian heart, said device having first and second ends, wherein
said device is sized and shaped to extend from septum secundum,
into the left atrium, through septum primum, and into the right
atrium, said first and second ends cooperating to provide a
compressive force to the overlapping layers of tissue.
2. The device of claim 1, wherein said first end is embedded in,
and does not extend through, septum secundum.
3. The device of claim 2, wherein said first end is formed into a
coil, hook, corkscrew, or other anchor.
4. The device of claim 1, wherein said first end includes a
material selected from the group consisting of bioresorbable
materials, noble metals, shape memory materials, metals, polymeric
materials, and swellable foams.
5. The device of claim 4, wherein said shape memory material
includes nitinol.
6. The device of claim 1, wherein said first end includes a septal
puncture needle capable of puncturing mammalian tissue.
7. The device of claim 1, further comprising a catheter containing
said device in an elongated, low-profile form, said first end being
expandable to form an anchor and said second end being adjustable
to alter a compressive force applied to the overlapping layers of
tissue.
8. The device of claim 1, wherein said device is sized and shaped
to further extend to septum secundum in the right atrium.
9. The device of claim 8, wherein said device includes a ring with
a gap terminating in first and second opposed, pointed ends for
puncturing mammalian tissue.
10. The device of claim 9, wherein said device includes a material
selected from the group consisting of flexible polymers,
bioabsorbable materials, spring metals, and shape memory
materials.
11. The device of claim 10, wherein said device includes
nitinol.
12. The device of claim 9, wherein said device consists essentially
of a monolithic partial ring.
13. The device of claim 9, wherein said device includes a gap
slightly smaller than the thickness of the overlapping layers of
tissue to which it is connected.
14. The device of claim 9, wherein said device includes a gap
slightly smaller than the thickness of septum secundum.
15. The device of claim 9, wherein said first and second ends
overlap each other.
16. The device of claim 1, wherein said device includes a partial
ring with first and second ends and at least one fold
therebetween.
17. The device of claim 16, wherein said at least one fold
cooperates with said first and second ends to apply a compressive
force to said overlapping layers of tissue.
18. The device of claim 16, wherein said device consists
essentially of a monolithic partial ring.
19. The device of claim 1, wherein said device is sized and shaped
to further contact the surfaces of septum primum exposed in both
the left and right atria.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This Application is a Divisional of U.S. patent application
Ser. No. 10/341,802, entitled Patent Foramen Ovale (PFO) Closure
Method and Device, filed Jan. 14, 2003, and incorporated herein by
this reference.
FIELD OF THE INVENTION
[0002] The invention relates to occlusion devices and methods for
the closure of physical anomalies, like septal apertures, such as
patent foramen ovale and other septal and vascular defects.
BACKGROUND OF THE INVENTION
[0003] A patent foramen ovale (PFO) as shown in FIG. 1, is a
persistent, one-way, usually flap-like opening in the wall between
the right atrium 10 and left atrium 12 of the heart. Since left
atrial (LA) pressure is normally higher than right atrial (RA)
pressure, the flap typically stays closed. Under certain
conditions, however, RA pressure can exceed LA pressure creating
the possibility for right to left shunting that can allow blood
clots to enter the systemic circulation. In utero, the foramen
ovale serves as a physiologic conduit for right-to-left shunting.
After birth, with the establishment of pulmonary circulation, the
increased left atrial blood flow and pressure results in functional
closure of the foramen ovale. This functional closure is
subsequently followed by anatomical closure of the two over-lapping
layers of tissue: septum primum 14 and septum secundum 16. However,
a PFO has been shown to persist in a number of adults.
[0004] The cause of ischemic stroke remains cryptogenic (of unknown
origin) in approximately 40% of cases. Especially in young
patients, paradoxical embolism via a PFO is considered in the
diagnosis. While there is currently no proof for a cause-effect
relationship, many studies have confirmed a strong association
between the presence of a PFO and the risk for paradoxical embolism
or stroke. In addition, there is good evidence that patients with
PFO and paradoxical embolism are at increased risk for future,
recurrent cerebrovascular events.
[0005] The presence of a PFO has no therapeutic consequence in
otherwise healthy adults. In contrast, patients suffering a stroke
or transient ischemic attack (TIA) in the presence of a PFO and
without another cause of ischemic stroke are considered for
prophylactic medical therapy to reduce the risk of a recurrent
embolic event. These patients are commonly treated with oral
anticoagulants, which have the potential for adverse side effects,
such as hemorrhaging, hematoma, and interactions with a variety of
other drugs.
[0006] In certain cases, such as when anticoagulation is
contraindicated, surgery may be used to close the PFO. To suture a
PFO closed requires attachment of septum secundum to septum primum
with either an interrupted or a continuous stitch, which is the
common way a surgeon shuts the PFO under direct visualization.
[0007] Nonsurgical closure of PFOs has become possible with the
advent of umbrella devices and a variety of other similar
mechanical closure designs, developed initially for percutaneous
closure of atrial septal defects (ASD). These devices allow
patients to avoid the potential side effects often associated with
anticoagulation therapies.
[0008] Currently available designs of septal closure devices,
however, present such drawbacks as technical complexity of
implantation procedure, high complication rates (thrombus,
fractures, conduction system disturbances, perforations, residual
leaks), high septal profile, large masses of foreign material, and
lack of anatomic conformability especially to the PFO flap-like
anatomy, as most were originally designed to close ASD's, which are
true holes. Additionally, some septal closure devices are complex
to manufacture, which can result in lack of consistency in product
performance.
SUMMARY OF THE INVENTION
[0009] In one aspect, the present invention provides a method of
closing two overlapping layers of tissue in a mammalian heart,
e.g., a patent foramen ovale (PFO), using a closure device that
applies a compressive force to at least one of the layers of
tissue. The closure device may be retrievable, such that it may be
removed after a period of time sufficient to allow the overlapping
layers of tissue to fuse together. If necessary to sufficiently
close the length of the layers of tissue, multiple closure devices
may be administered. The closure devices may be delivered with a
catheter capable of puncturing mammalian tissue in at least one
location.
[0010] The closure device of the present invention may take a
number of different forms. For example, the closure device may have
first and second ends, both of which may be capable of puncturing
mammalian tissue. The device may be a structure such as a ring with
a gap, a folded ring, at least one grappling hook member joined to
at least one curved arm by a joinder member, opposed grappling hook
members joined by a central connecting member, a grappling hook
member and a central connecting member, or a closure device anchor
joined to a structure of sufficient diameter to hold the device in
place against the overlapping layers of tissue. In some embodiments
of the present invention, the closure device is sized and shaped
such that it extends from septum secundum in the left atrium, into
the left atrium, through septum primum, into the right atrium, and
to septum secundum in the right atrium. Some retrievable devices
include elongate tethers to facilitate their removal. Each of these
devices has certain advantages, and one skilled in the art will be
capable of selecting the device appropriate for a given
application.
[0011] The ends of the closure device may also take a number of
different forms. For example, at least one end may form a disc or a
closure device anchor, such as a coil, hook, or corkscrew. These
end structures help to maintain the device in place. One of the
ends, for example the second end, may take the form of a knot or a
structure similarly capable of holding the device in place and
applying a sufficient compressive force to the overlapping layers
of tissue. In some embodiments, the end structure may be adjusted
to alter the compressive force applied to the overlapping layers of
tissue. As previously mentioned, either or both of the first and
second ends may be capable of puncturing mammalian tissue. In some
embodiments, the first end of the device is a septal puncture
needle.
[0012] The closure device may be formed of any of several
materials, such as flexible polymer materials, bioabsorbable
materials, shape memory materials, metals, noble metals, or
swellable foams. In particular embodiments, the device includes
nitinol. Some of the devices are formed from a single piece of
material, while others are formed from multiple pieces of material
joined together.
[0013] Some closure devices according to the present invention are
intended to puncture septum primum upon insertion into the heart.
For example, such a device may be inserted into the right atrium of
the heart and puncture septum primum to enter the left atrium of
the heart. At this point, the first end of the device may simply be
deployed into the left atrium, or the first end of the device may
be deployed into the left atrium and at least partially puncture
septum secundum. In those embodiments where the first end of the
device at least partially punctures septum secundum, the first end
may be embedded in septum secundum or may completely puncture
septum secundum such that the first end extends into the right
atrium. The second end of the device may then be positioned against
septum secundum in the right atrium, thereby providing a
compressive force to the septal tissues. In other embodiments, the
second end is also positioned in the left atrium while another
portion of the device, such as a fold, is positioned in the right
atrium, thereby compressing the septal tissues between the
device.
[0014] Alternatively, some closure devices according to the present
invention are intended to be inserted between the overlapping
layers of tissue, e.g. through the PFO tunnel, to enter the left
atrium. In these embodiments, the first end of the device is then
deployed in the left atrium and the second end of the device is
deployed in the right atrium, thereby providing a compressive force
to the septal tissue. As discussed above, at least one of the ends
of the device may partially puncture septum secundum.
[0015] These and other features will become readily apparent from
the following detailed description wherein embodiments of the
invention are shown and described by way of illustration.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a diagrammatic sectional view of a Patent Foramen
Ovale (PFO);
[0017] FIG. 2 is a view in side elevation of the PFO closure device
with mechanical anchors of the present invention;
[0018] FIGS. 3a, 3b and 3c illustrate the steps in the deployment
of the PFO closure device of FIG. 2;
[0019] FIG. 4 is a view in side elevation of a second embodiment of
the PFO closure device with mechanical anchors of the present
invention;
[0020] FIGS. 5a, 5b and 5c illustrate the steps in the deployment
of the PFO closure device of FIG. 4;
[0021] FIG. 6 is a view in side elevation of a catheter and septal
puncture needle used to pierce septum primum;
[0022] FIG. 7 is a view in side elevation of a needle anchor for
PFO closure;
[0023] FIG. 8 is a view in side elevation of a suture and anchor
used for PFO closure;
[0024] FIG. 9 is a diagram of multiple anchor placement for PFO
closure;
[0025] FIGS. 10a, 10b and 10c illustrate the steps in the
deployment of a rivet and suture type of PFO closure device;
[0026] FIGS. 11a, 11b, 11c and lid illustrate the steps in the
deployment of a removable PFO closure device;
[0027] FIGS. 12a, 12b and 12c illustrate the steps in the
deployment of a multiple hook PFO closure device;
[0028] FIG. 13 is a view in side elevation of an alternative
structure of the second embodiment of the PFO closure device with
mechanical anchors of the present invention;
[0029] FIG. 14 is a view in side elevation of an alternative
structure of the second embodiment of the PFO closure device with
mechanical anchors of the present invention; and
[0030] FIGS. 15a, 15b, and 15c are an end face view from the right
atrium, an end face view from the left atrium, and a side elevation
view, respectively, of the deployed alternative structure of the
second embodiment of the PFO closure device with mechanical anchors
of the present invention.
DETAILED DESCRIPTION
[0031] Referring to FIGS. 2 and 3, a PFO closure device with
mechanical anchors indicated generally at 18 includes opposed
grappling hook members 20 and 22 connected by a central connecting
member 24. When the PFO closure device 18 is deployed, the
grappling hook members 20 and 22 each include two or more curved
hooks. In FIGS. 2 and 3, three curved hooks 26, 28 and 30 form the
grappling hook member 20 and three curved hooks 32, 34 and 36 form
the grappling hook member 22. As shown in FIG. 2, the grappling
hooks 26, 28, 30, 32, 34, and 36 extend radially from the central
connecting member 24. The grappling hooks of grappling hook members
20 and 22 have the same geometry but are rotated such that each
grappling hook of grappling hook member 20 is situated precisely
between two opposed grappling hooks of grappling hook member 22.
The angle between any two grappling hooks of grappling hook members
20 and 22 may be determined by the formula 360.degree./(number of
hooks per grappling hook member). To fit within a catheter, these
hooks may all be straightened outwardly and compressed to lie along
the longitudinal axis of the central connecting member 24. In this
form, the PFO closure device extends longitudinally within a
catheter 38.
[0032] To deploy the PFO closure device 18, the catheter 38 is
inserted from the right atrium 10 through the PFO tunnel, i.e.
between septum primum 14 and septum secundum 16, into the left
atrium 12. As shown in FIG. 3a, the grappling hook member 20 is
deployed into the left atrium. Next, as shown in FIG. 3b, the
catheter 38 is drawn back into the right atrium and the grappling
hooks 26, 28 and 30 are drawn back and embedded in the left sides
of septum primum and septum secundum. The central connecting member
24 extends at an angle through the PFO tunnel permitting septum
primum and septum secundum to be drawn to the closed position and
secured by the grappling hooks 26, 28 and 30. Finally, as shown in
FIG. 3c, the catheter 38 is drawn back to permit the grappling hook
member 22 to deploy, and grappling hooks 32, 34 and 36 pierce the
right side of septum primum and septum secundum.
[0033] The grappling hook members 20 and 22 may be formed of
flexible, spring-like, bioabsorbable polymer material so as to
permit movement from the compressed straight shape to the curved
hook shapes following deployment from the catheter 38. The central
connecting member 24 may also be formed of bioabsorbable material,
such as an absorbable suture material, so the device will
ultimately leave no foreign substance in either atrium.
Alternatively, the grappling hook members 20 and 22 may be formed
of spring metal or of a shape memory material, such as nitinol.
When the PFO closure device is not formed of bioabsorbable
material, it is possible to form the device with only the grappling
hook member 20 and a central connecting member 24 so that the
device is repositionable and retrievable. When the device is made
of a bioabsorbable material or is not intended to be retrievable,
the ends of grappling hooks 26, 28, 30, 32, 34 and 36 may further
include a barb to maintain the device in the septal tissue. In some
embodiments, the grappling hook members 20 and 22 serve as tissue
scaffolds, and are covered with a vascular material, such as
polyester, biological tissue, bioresorbable polymer, or spongy
polymeric material.
[0034] As shown in FIG. 3, the closure device will conform, at
least to some extent, to the septal tissue that it compresses. The
extent of this conformance depends upon the material from which the
device was formed: a device formed of a spring metal or shape
memory material will conform to the surrounding septal tissue to a
lesser extent than one formed of a flexible, bioabsorbable polymer
material.
[0035] FIG. 4 shows a second embodiment of a PFO closure device
with mechanical anchors indicated generally at 40. This device,
when deployed, forms a ring hook design that terminates in two
opposed, pointed ends 42 and 44. The device may be straightened to
pass through a catheter 38. To deploy the device as shown in FIGS.
5a, 5b and 5c, the catheter is caused to pierce septum primum 14
and enter the left atrium where the pointed end 42 is deployed.
Then, as shown in FIG. 5b, the catheter is drawn back through
septum primum to draw the device through septum primum and embed
the pointed end 42 in the left side of septum secundum. Finally, as
shown in FIG. 5c, the catheter is withdrawn to fully deploy the PFO
closure device and the pointed end 44 is embedded in the right side
of septum secundum to compress septum primum and septum secundum
together. As shown in FIGS. 4 and 5, the ring PFO closure device
40, when deployed, may include a gap that is slightly smaller than
the thickness of septum secundum into which it is embedded. In some
embodiments, the opposed ends 42 and 44 of the deployed PFO closure
device 40 contact each other or overlap.
[0036] As shown in FIGS. 13 and 14, closure device 40 may take
alternative forms. For example, closure devices 90 and 100 are
formed as partial rings terminating in two pointed ends 92 and 94
or 102 and 104 and having at least one fold therebetween. Closure
devices 90 and 100 are deployed in a manner similar to that
described above and shown in FIG. 5. When deployed, the pointed
ends 92 and 94 or 102 and 104 puncture the surface of septum
secundum exposed in the left atrium and at least one of the folds
contacts the surface of septum secundum exposed in the right atrium
(FIGS. 15a and 15b). Septum primum and septum secundum are thus
compressed between the pointed ends and at least one of the folds
of the device (FIG. 15c).
[0037] Multiple PFO closure devices 40, 90 or 100 can be inserted
until the physician is satisfied with the resultant PFO closure.
Again, the PFO closure devices may be formed of flexible,
bioabsorbable polymer material, spring metal, other spring-like
non-bioabsorbable material, or shape memory material. The choice of
material will affect the degree to which the device conforms to the
surrounding septal tissue. As shown in FIGS. 4, 13, and 14, the PFO
closure device may be a monolithic structure.
[0038] A PFO may also be closed with one or more sutures. As used
in the art and indicated in the Figures, "suture" refers to a
single connection used to hold two pieces of material or tissue
together and need not be a continuous stitch. However, to suture a
PFO closed has conventionally required the attachment of septum
secundum to septum primum with a continuous stitch. This need for a
continuous stitch can be eliminated by implanting sutures across
the PFO using implantable suture anchors. As shown in FIGS. 6 and
7, a catheter 46 is used to puncture septum primum and then septum
secundum. In the case of septum primum, the puncture creates a hole
through which the catheter can pass; in the case of septum
secundum, the puncture may be a depression that does not pass
through septum secundum. A single puncture may be made in septum
secundum as shown in FIGS. 6-8, or, as subsequently described and
shown in FIG. 9, multiple punctures may be made. These punctures
are made using a sharp pointed needle tip 48. Following puncture to
a desired depth, the catheter 46 surrounding the needle 48 is
withdrawn and the needle component returns (most likely via shape
memory) to its predetermined anchor-shape.
[0039] The anchors are most likely fabricated from a shape memory
alloy, such as nitinol, although they could be made from a
flexible, bioabsorbable polymer or a noble metal, each having their
own advantage--no long term implant issues with bioabsorbable
anchors and excellent radiopacity with anchors fabricated from a
noble metal, such as platinum-iridium. The remainder of the suture
may be formed of any suitable material, including wire, polymeric
materials, and bioabsorbable materials.
[0040] The suturing method includes using a standard septal
puncture technique to locate and puncture septum primum. Following
this, several approaches exist. One would be that the septal
puncture needle would be withdrawn from the catheter and the
suturing system then delivered through the catheter (the septal
needle catheter would maintain position across septum primum during
the exchange). Alternatively, a wire could be placed through the
septal needle catheter to maintain position and the suture system
could be delivered over the wire, or the septal puncture needle
could become part of the suture system. Following delivery of the
suture system, the proximal end of the suture may then be tied off
so as to secure the system in place and keep the PFO closed. As
described below for the rivet design suture system and shown in
FIG. 10c, the proximal end of the suture may be formed into a knot,
i.e. the end of the suture may be formed into a structure having a
diameter larger than that of the catheter used to puncture septum
primum so as to ensure that the suture system remains in place.
Other suitable structures for the proximal end of the suture
include, but are not limited to, coils, spirals, and other
adjustable mechanisms. This structure should apply sufficient
compression to hold septum primum and septum secundum together. The
structure may be adjustable, such that the level of compression may
be altered as necessary. Multiple sutures may be inserted until the
physician is satisfied with the PFO closure.
[0041] In FIG. 8, a suture 50 is delivered through the septal
needle catheter following the removal of the needle. A suture
catheter 52 enters the left atrium through the septal needle
catheter, is pulled back against septum secundum, setting the
needle tip(s) 54 deep within it or through it, if it is thin
enough. The tip could be either radiopaque, echogenic, or both, to
be visible by x-ray (fluoroscopy) and/or cardiac echo. Once proper
position is determined, the constricting system (a hypotube or a
series of con-axial hypotubes in the embodiment where multiple
needles are simultaneously delivered) is withdrawn, allowing the
suture anchor 56 to form into a pre-determined shape tissue anchor,
most likely via shape memory properties. The anchor 56 on the end
of the suture 50 has been embedded in septum secundum and expands
to anchor the suture, which passes through septum primum once the
suture catheter is removed. The anchor shape can be one of many
different options, including but not limited to a coil, hook,
corkscrew, or grappling hook.
[0042] In those cases where a true puncture through septum secundum
can be made, an anchor can be placed entirely in the right atrium,
leaving nothing but suture in the left atrium. These anchors may be
short strips or cylindrical rods made from a metallic or polymeric
material that is biostable or bioabsorbable, or a piece of
swellable foam, such as Ivalon.
[0043] In another embodiment, the septal needle catheter crosses
septum secundum in multiple locations simultaneously. In this
embodiment, the final result, as seen from the left atrium in an
end face view of septum primum and septum secundum, would be as
shown in FIG. 9, where a plurality of spaced anchors 58 engage
septum secundum.
[0044] A rivet design suture system 60 is shown in FIGS. 10a, 10b
and 10c. Here a suture 62 and anchor 64 are contained within a
catheter 66, which pierces both septum secundum and septum primum.
The anchor 64, which is formed of a firm material, such as a metal
disc, a small hook (such as the shape memory hooks previously
described), or a piece of bio-absorbable polymer, is then deployed
into the left atrium, and the suture 62 and catheter 66 are then
pulled back as shown in FIG. 10b to compress the two septa
together. The suture 62 can then be knotted with knot 68, as shown
in FIG. 10c, to secure the system 60 in place to keep the PFO
closed, i.e. the end of the suture may be formed into a structure
having a diameter larger than that of the catheter used to puncture
septum primum so as to ensure that the suture system remains in
place. Other suitable structures for the second end of the suture
include, but are not limited to, coils, spirals, other adjustable
mechanisms. As shown in FIG. 10c, this structure should apply
sufficient compression to hold septum primum and septum secundum
together. The structure may be adjustable, such that the level of
compression may be altered as necessary. Multiple rivet systems can
be inserted until a physician is satisfied with the PFO
closure.
[0045] The PFO closure device of the present invention may be
formed in a manner to facilitate removal once septum primum and
septum secundum are fused. An exemplary removable PFO closure
device 70 is deployed in the manner illustrated by FIGS. 11a-11d.
The PFO closure device 70 may be delivered by a delivery catheter
or sheath 72 and includes a grappling hook member 74 joined to a
curved arm 76 by an enlarged tip joinder member 78. At least one of
the grappling hook member and curved arm of the PFO closure device
may be curved relative to the other. An elongate tether 80 is
connected to the tip joinder member 78 and extends back through the
catheter 72. The tether 80 can be coated to minimize trauma to the
veins.
[0046] To deploy the removable PFO closure device 70 according to
one embodiment of the invention, the grappling hook member 74 is
passed through septum primum 14 (FIG. 11b), and the grappling hook,
when free of the catheter, curves in a manner convex relative to
the surface of septum secundum and penetrates septum secundum 16
(FIG. 11c). Then, the grappling hook is drawn back toward the
catheter by the tether 80 to apply tension to the tissue causing
septum secundum to be drawn into contact with septum primum. Then
the curved arm 76 is deployed (FIG. 11d) and curves in a manner
concave relative to septum secundum so as to engage septum secundum
as the catheter is drawn back. The compressive force applied by the
grappling hook and the curved arm hold septum primum and septum
secundum tightly together. The grappling hook 74 and curved arm 76
are preferably formed of shape memory material, such as nitinol, so
that they respond to body temperature when deployed from the
catheter 72 to form the shape shown in FIG. 11d.
[0047] Once the PFO closure device 70 is in place, the catheter 72
is withdrawn and the free end of the tether 80 is attached to a
button subcutaneously and allowed to remain in place for a period
of time sufficient to allow the two septa to fuse together. Then
the device is pulled through septum primum and into a recovery
sheath by means of the tether 80 and removed.
[0048] The PFO closure device 70 can be deployed as shown in FIG.
11 without the tether 80 to provide a free standing device with the
grappling hook 74 and arm 76 being formed to press the two septa 14
and 16 together. The device may later be removed by a removal
device, which grabs the joinder member 78 and draws the device
through septum primum 14 and into a removal sheath.
[0049] Instead of a single opposed grappling hook 74 and curved arm
76, the PFO closure device can include a plurality of opposed
grappling hooks and curved arms radially extending in a spaced
relationship from the joinder member 78. Such a device 82 is shown
in FIG. 12. Here, the PFO closure device includes a plurality of
grappling hooks 84 and a plurality of opposed curved arms 86 which
are enclosed in a delivery catheter 72. A small hole 88 is created
in septum primum 14 to permit insertion of the catheter into the
left atrium and the grappling hooks 84 are deployed as shown in
FIG. 12a. Then, the delivery catheter is drawn back to engage the
hooks with both septum secundum and septum primum as shown in FIG.
12b. Next, as shown in FIG. 12c, the catheter is drawn away to
release the curved arms 86, which engage the two septa in opposed
relationship to the grappling hooks 84. The device may have many,
e.g. eight, opposed grappling hooks and curved arms. As in the case
of the PFO closure device 70, the device 82 may be removed by
grasping the tip joinder member 78.
[0050] The device 82 may be permanently deployed by inserting the
catheter through the PFO channel between septum secundum and septum
primum into the left atrium to deploy the grappling hooks 84. Then,
the catheter is withdrawn back through the PFO channel to release
the curved arms 86.
[0051] Having described embodiments of the present invention, it
should be apparent that the invention is capable of other and
different embodiments and may be modified in various respects, all
without departing from the scope of the invention as defined by the
appended claims. Accordingly, the foregoing drawings and
description are to be regarded as illustrative in nature and not in
a restrictive or limiting sense.
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